Lateral sacroiliac joint fusion

Introduction

Sacroiliac joint (SIJ) disease has been increasingly recognized as a common contributor to many cases of lower back pain (LBP) and radiculopathy, with a prevalence estimated at between 13% and 30% in patients with LBP. ^, Although the cause of SIJ pain is not fully understood, it is thought to be inflammation and injury to nociceptors throughout the joint capsule and ligaments following trauma or repeated stresses. SIJ fusion alleviates pain through providing stability to the joint and preventing excessive motion. Surgical treatment of SIJ pathologies through fusion of the ilium and sacrum has been demonstrated to significantly decrease pain and disability with appropriately selected patients using several techniques. ^, Although historically performed through both open and minimally invasive techniques, less invasive methods of fusion have become the dominant method of SIJ fusion.

This chapter discusses minimally invasive lateral approaches to SIJ fusion tat attempt to fuse the bone by placement of an implant through the ilium and across the SIJ. These surgeries have short operative times, are associated with low blood loss, and can be performed in an outpatient setting. Common methods of achieving fusion through a lateral approach include percutaneous placement of bone plugs or screws with bone graft; the latter is discussed in this chapter.

Indications

Sacroiliac joint fusion is indicated for the treatment of SIJ pain for patients with low back and/or buttock pain who meet all of the following criteria:

1.

Underwent and failed a minimum of 6 months of intensive nonoperative treatment that includes medication optimization, activity modification, and active physical therapy
2.

Report unilateral and/or bilateral pain that is at or near the L5 vertebrae, localized over the posterior SIJ, and consistent with SIJ pain. (Pain radiating down the leg does not rule out SIJ disease.)
3.

Report localized tenderness with palpation of the posterior SIJ and/or groin in the absence of tenderness of similar severity elsewhere and other obvious sources for the pain do not exist (Fortin’s test).
4.

Have a positive response to the thigh thrust test or compression test and two of the following additional provocation tests:
- a.
  
  Gaenslen’s test
- b.
  
  Distraction test
- c.
  
  Patrick’s sign
- d.
  
  FABER (flexion, abduction, and external rotation) test
- e.
  
  Fortin’s test
5.

Have an absence of generalized pain behavior (e.g., somatoform disorder) and generalized pain disorders (e.g., fibromyalgia). If these are present, diagnoses have been ruled out as the source of the patient’s pain.
6.

Diagnostic imaging studies that include all of the following:
- a.
  
  Imaging of the SIJ that excludes the presence of destructive lesions or inflammatory arthropathy that would not be properly addressed by percutaneous SIJ fusion
- b.
  
  Imaging of the ipsilateral hip to rule out osteoarthritis
- c.
  
  Imaging of the lumbar spine to rule out neural compression and other degenerative conditions that can cause low back or buttock pain
7.

Have at least 75% reduction of pain for the expected duration of the anesthetic (hours to days) used following an image-guided, contrast-enhanced SI injection on two or three separate occasions

Contraindications

Sacroiliac joint fusion for SIJ pain is NOT indicated in any of the following scenarios, except in specific circumstances when other pathologies have been investigated separately and ruled out as a source of pain:

1.

Any case that does not fulfill all of the above criteria
2.

The presence of systemic arthropathy such as ankylosing spondylitis or rheumatoid arthritis
3.

The presence of generalized pain behavior or generalized pain disorder
4.

The presence of infection, tumor, or fracture
5.

The presence of neural compression as seen on magnetic resonance imaging or computed tomography that correlates with the patient’s symptoms and is most likely the source of their pain

Preoperative considerations

Routine patient evaluation for risk of infection, use of anticoagulation, and addressing all comorbidities that may impact the operative course should be done.

Preoperatively, the patient is induced and placed in the prone position on a Jackson table. The area around the patient’s SIJ is prepared, and the draping is performed before surgery. Intraoperatively, 1% lidocaine with epinephrine and 0.25% Marcaine plain mixed 1:1 is injected at the skin where the incision will be made.

Postoperative care

The patient is usually discharged within 4 hours of the case, almost always the same day as the surgery. The patient is discharged with pain medication and muscle relaxants. If there is excess bleeding, an ACE wrap is used to compress the surgical site. Patients are typically able to walk with a walker immediately after surgery with toe-touch weight-bearing restrictions for 2 to 4 weeks.

Complications

Complications of minimally invasive SIJ fusion include the following:

1.

Rare cases of higher blood loss if the iliac crest is violated during the procedure. This is treated with an ACE bandage wrap around the patient’s torso and the surgical site.
2.

Loosening of screws requiring revision, mostly seen in cases of falls after the procedure before fusion has been achieved. Serial diagnostic SIJ injections are performed before revision to confirm that hardware loosening is responsible for clinical symptoms.
3.

In our practice, we observed one case of gluteal hematoma requiring evacuation that was later found to have an iliac artery pseudoaneurysm requiring coiling.
4.

Wound dehiscence has been rarely observed and treated by secondary intention with local wound care.

Background

Imaging and anatomy

Three radiography positions are used in this technique: lateral ( Fig. 8.1 ), inlet ( Fig. 8.2 ), and outlet ( Fig. 8.3 ). The inlet view displays the true axial view of the first three sacral vertebrae and is achieved by tilting the x-ray tube cephalad ( Fig. 8.4 ). The outlet view is the true anterior view of the sacrum and is achieved by tilting the x-ray beam caudally ( Fig. 8.5 ).

Transiliac arch screws

Postoperative imaging demonstrating completed SIJ fusion using this technique is seen in Figure 8.6 .

Preoperative planning

The appropriate size of implant should be selected before surgery. The implant size can be estimated by measuring the length of a line perpendicular to the outer boundary of the ilium to the first sacral foramen in the axial view ( Fig. 8.7 ).

Targeting

The patient is placed in the prone position on the operative table. C-arm fluoroscopy is used to provide imaging during the procedure. Neuromonitoring may be used to monitor muscles throughout the procedure for increased safety.

Lateral fluoroscopy should be used to visualize the trochanteric notch and ala ( Fig. 8.8 ).

Mark the sacral shadow on the skin and draw a line from the sacral promontory to the middle of the sciatic notch using a guide pin and marking pen. The skin incision is made 1 inch perpendicularly above this line at the middle of the sciatic notch ( Figs. 8.9 and 8.10 ).

Insert the blunt end of the guide pin lateral to medial through the incision and place guide pin on the ilium about 1 inch caudal to the shadow of the ala and aligned with the anterior wall of the sacrum for the first screw placed ( Fig. 8.11 ). We make contact with the iliac crest so that it aligns with the S1 to S2 foramen in the lateral view ( Fig. 8.12 ).